This invention relates to a vapor recovery and condensing system and, more particularly, to such a system in which vapors are recovered from a liquid process or storage tank, condensed, and passed back to the tank.
With the increased emphasis on preventing pollution of the atmosphere, recent attention has been directed to minimizing the introduction of vapors into the atmosphere from permanent type underground storage tanks, solvent cleaning processes, or the like. Taking gasoline as an example, underground storage tanks are provided at service stations which are periodically filled by transport trucks which, in turn, receive the gasoline from regionally located bulk storage tanks. Gasoline vapors accumulate in the upper portions of the tanks at the service stations and the bulk storage tanks as a result of natural vaporization of the gasoline in the tanks. Also, additional air and vapors may be drawn into the storage tanks at some service stations from the vehicle tanks by virtue of use of vapor recovery equipment, or the like.
As a result of this accumulation of air and vapors, vent pipes or the like, are presently provided on each of the storage tanks for venting the vapors to atmosphere.
Previously it has been proposed to condense the vapors from the tanks and venting only the remaining air to atmosphere using refrigeration or carbon absorption systems, or the like, which are very complex and costly.